对Si3N4颗粒及SiC晶须强韧化MoSi2复合材料在773K下的氧化行为进行了研究.通过热重量分析法（TG）分析了MoSi2及其复合材料MoSi2-Si3N4(p)和MoSi2-Si3N4(P)SiC(w)在773K下的氧化性能, 采用SEM和X射线衍射测定其表面形貌和氧化物相组成.结果发现：在773K下, 纯MoSi2和MoSi2+20vol%Si3N4均发生了“Pesting”氧化, 氧化过程服从直线规律, 氧化产物层疏松, 氧化产物主要为MoO3; MoSi2+40vol%Si3N4氧化服从抛物线规律, 速率常数Kp为0.04mg2/(cm4·h), 氧化层致密, 成分主要为SiO2、Si2N2O, 增加Si3N4的含量可显著提高MoSi2的抗“Pesting”氧化能力; MoSi2+20vol%Si3N4+20vol%SiC发生了严重的粉化现象, 氧化产物主要为短针状MoO3.
The oxidation behavior of MoSi2 composites strengthened and toughened by Si3N4 particles and SiC whiskers was investigated. The oxidation performances of pure MoSi2, MoSi2-Si3N4(p) and MoSi2+20vol%Si3N4+20vol%SiC at 773K were analyzed by thermo gravimetric analysis(TG). The surface micrograph and phases of the oxidation productions were analyzed using by SEM and X-ray. “Pesting” phenomena are observed in the pure MoSi2 and MoSi2+20vol%Si3N4 after oxidation, the relationship between gain weight and oxidation time is followed the straight-line law. The oxidation layer is loose and the main oxidation production is MoO3. While the relationship between the gain weight and oxidation time is followed parabolic law during the oxidation of MoSi2+40vol%Si3N4 and the oxidation rate is 0.04mg2/(cm4·h). The oxidation layer is dense and the main oxidation productions are SiO2 and Si2N2O. So the resistance to “Pesting” oxidation will increase with the content of Si3N4 increasing. There happens serious “Pesting” in the MoSi2+20vol%Si3N4+20vol%SiC after oxidation and the main oxidation production is short acicular MoO3.
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